As a child in Auschwitz, Otto Dov Kulka came into contact with a choir conductor nicknamed Imre, “a big man; quite huge”. Imre organised a children’s choir and rehearsed them in one of the barracks that were used as lavatories. The song and the melody they sang was unfamiliar to Kulka; later in the camp he learned to play it on the harmonica and this book reproduces the first few bars. It was Beethoven’s “Ode to Joy”.

Kulka has spent over 60 years pondering Imre’s motivation. Was it a protest, albeit without any practical purpose, a devotion to values of which Auschwitz was the opposite? “As long as a man breathes, he breathes freedom, something like that?” Kulka wonders. He has a second speculative explanation: that it was “an act of extreme sarcasm . . . In other words, this was a kind of almost demonic self-amusement.”

According to the footnotes, Imre’s real name was Emmerich Acs and he died in the gas chamber on 8 March 1944. The child in the choir became one of the leading Israeli historians of the Holocaust, an academic who describes himself as possessing “an attitude of strict and impersonally remote research, always conducted within welldefined historical categories”. Kulka’s short book of memoir and inquiry consists of ten chapters that are transcripts of tape recordings he made in the 1990s, followed by three extracts from his diaries. It is almost unclassifiable. Like Fatelessness, a novel by another child inmate of the camps, Imre Kertész, it tries to penetrate the maze of established fact and personal experience in order to arrive at what seems unreachable.

Death, not life, is what this book is about – the “Great Death”, the “Metropolis of Death”. When, in the mid-1990s, I visited Auschwitz- Birkenau – the non-tourist section of the camp, the one without the “Arbeit macht frei” gates and the gift shop, but the site of the mass-extermination of Europe’s Jews – what struck me was its scale. It extended from horizon to horizon. There was nothing but the camp and the sky, from which no relief came. Until the liberation, no one held there ever left except on a death march. The unusual aspect of the Nazi extermination camps – including Treblinka, of which nothing remains but a clearing in the forest –was the frenzied intensity, the number of deaths in such a short duration and the near-impossibility of escaping before it was all over.

As one of the small number of survivors, Kulka describes the camps’ “trans-dimensionality”, “their vast impersonality”. Once the Shoah becomes material for research and the subjective vault of personal memory, it is almost possible to penetrate it. For Kulka, the past is something he has tried to smash his way back into, as both scholar and survivor. What he knows is that while the past lies behind an impenetrable membrane, the immutable law of the Great Death is now part of the world, which “will never again be able to free itself of [its] being part of its existence”.

Holocaust deniers swarm on the internet demanding that they should be allowed to ask questions. The Holocaust has been subjected to more forensic questioning than any other event in history. The weight of research is now enormous, though the event itself still defeats our attempts to understand it. For Kulka, attempts to explain the Shoah leave him feeling baffled; he reads nothing literary or artistic, has not seen Claude Lanzmann’s film Shoah and, though he works in the archives and library at Yad Vashem, he has not visited the exhibition there. He arrives at the startling conclusion that whatever is expressed about Auschwitz has no resonance for him: “It is a completely dif - ferent world!” Only in the interior realm of memory can he find a way into his private mythology.

Nothing else I have read comes close to this profound examination of what the Holocaust means. Kulka looks everywhere for loopholes in the immutability of death. His journey strikes me as a quest similar to the attempt to describe the face of God or the structure of the universe. They are too vast and too mysterious. Not that this stops us, or this author, from trying.

Linda Grant’s most recent novel is “We Had It So Good” (Virago, £7.99)